Organic-bonded abrasive containing octachloronaphthalene filler

ABSTRACT

In an organic-bonded abrasive product comprising abrasive material and an organic binder, the improvement comprising adding to said abrasive material and binder an effective amount of a completely chlorinated hydrocarbon whose carbon skeleton consists only of aromatic carbon atoms.

United States Patent 1191 Daniels 5 1/298 Caserta et al. Jan. 8, 1974 [5 ORGANIC-BONDED ABRASIVE 3,321,287 5/1967 Hunsbergerun'; 51/293 CONTAINING 3,502,453 3/l970 Baratto 51/29 5 OCTACHLORONAPHTHALENE FILLER [75] Inventors: Richard T. Caserta, Lansdale;

Primary Examiner-Donald J. Arnold 2:32 21. gg Phlladelphla Attorney-Caesar, Rivise, Bernstein & Cohen [73] Assignee: Red Hill Grinding Wheel Corporation, Pennsburgh, Pa. [22] Filed: Apr. 6; I971 57 ABSTRACT [21] Appl. No.: 131,778 I 5 In an organic-bonded abrasive product comprising 521 US. Cl 51/298, 51/295 51/306 abrasive material and an Organic binder the impmve [51] Int. Cl C08 g 51/12 ment comprising adding to Said abrasive material and [58 Field of Search 51/295 298 306 binder an effective amwmof a Completely chlmi' nated hydrocarbon whose carbon skeleton consist [56] References Cited only of aromatic carbon atoms.

UNITED STATES PATENTS 2 Claims, No Drawings This invention relates to an organic-bonded abrasive product, such as a grinding wheel, abrasive segment, abrasive cylinder, mandrel-mounted abrasive body, and any other three dimensional shapes of organicbonded products known to the art. lt provides a unique void-replacement material, and has as its objective the provision of a new and improved bonded abrasive product. i

A grinding wheel or other organic-bonded abrasive product basically consists of an abrasive material such as fused aluminum oxide, (and/or various modifications thereof), silicon carbide, diamond or natural corundum, with such abrasive material being held together by one or more organic polymeric binder materials.

Such organic materials are phenol-formaldehyde resin and various modifications thereof, natural and synthetic rubber, shellac, epoxy resin, polyester resin. The polymeric binders can also contain many inorganic fillers known in the art such as cryolite (Na AlF lime (CaO), iron pyrites (FeS- potassium fluoroborate (KBF potassium aluminum'fluoride (K AlF common salt (NaCl), sodium sulfate (Na SO potassium sulfate (K 80 zinc sulfate (ZnSO stibnite (Sb S and zinc sulfide (ZnS).

It is generally known that an abrasive-binder formulation may be pressed to a desired porosity. As the wheeel is pressed to a lower porosity, it becomes harder which usually results in a longer life for the abrasive product. Unfortunately, the metal removal rate usually drops with increasing wheel hardness.

Accordingly, the manufacture of a grinding wheel usually involves an attempt to strike a compromise between the higher metal removal rate obtainable. with softer wheels and longer life obtainable with harder wheels.

The present invention arises from the observation that a unique material may be included with the mixture of abrasive and binder, which will replace part of the voids, and which will achieve a lubricating action that will improve the cutting characteristics of the wheel and/or extend the wheel'life.

In particular, the present invention contemplates the addition of an effective amount of a completely chlorinated hydrocarbon whose carbon skeleton consists only of aromatic carbon atoms. For the sake of brevity, those materials (or substances) that are included for the sake of achieving a better cutting action and/or longer life will be referred to as the aromatic chlorine compounds usable in the invention.

Furthermore, it has been discovered that the aromatic chlorine compounds usable in the invention are preferably selected from thegroup consisting of octachloronaphthalene, decachlorobiphenyl and hexachlorobenzene.

Each of the foregoing compounds are aromatic carbon compounds in which all hydrogen has been replaced by chlorine. These three compounds are chemically inert during the curing of the wheel and so will not chemically combine with the resin, abrasive, or any other component of the wheel formulation. lt will be appreciated that aliphatic compounds or groups do not fall within the scope of compounds usable in the invention since it is known that aliphatically bonded chlorine 2 will become involved in condensation reactions with other components of the wheel formulation.

It has been determined that the aromatic chlorine compounds usable in the invention are preferablypresent in an amount not less than ,l percent by weight of the total mix and not greater than 1 6 percent by weight of the total mix. It has also been determined that minor amounts of the aromatic chlorine compounds, less than 1 percent, will not achieve'a significant improvement in abrasive product performance. In percentages above 16 percent, it has been determined that the strength of V the wheel will decline since the aromatic chlorine compounds will then occupy a relatively high percentage of the voids in the wheel, and the resin binder becomes insufficient in quantity to maintain a strong, consolidated mass.

In order to determine how the presence of octachloronaphthalene affects the strength characteristics, an abrasive mix was formulated having the following ingredients by weight:

l. Abrasive grain 88% l/3 each 20, 24, 30

mesh Fused A1 0 2. Resin, powdered 10% Phenolic Resin, catalyzed by Hexamethylene Tetramine 3. Furfural (wetting agent) 1.30%

4. Carbosota (neutral anthracene coal tar fraction lt is to be noted that the foregoing mix does not contain an aromatic chlorine compound usable in the invention. It was pressed to a density of 2.192 grams per cc and had thirty per cent voids (all air). A series of gram test bars were produced from the foregoing asrmarsataaiigaiafiswas of 6% inches length, 1 inch width and "la inch depth.

The foregoing formula was repeated with the introduction of two per cent by weight of octachloronaphthalene to produce a bar having a density of 2.236 wherein the thirty per centvoids consisted of 27.66 air and 2.33 aromatic chlorine compounds to produce 179 gram bars.

The following table shows further formulations in this series:

% Aromatic gm/cc Division of 30% Weight Chlorine Compounds Density Voids of Bars 4 2.280 25.33 air l83 4.67 aromatic 6 2.324 23.00 air 186 7.00 aromatic 8 2.367 20.67 air I89 9.33ar0matic 10 2.41] 18.33 air 193 l 1.67 aromatic Strength tests showed that the test bars increased in strength until an optimum strength was obtained in the region between 6 and 8 percent aromatic chlorine compounds. Interpolation by the method of least squares predicted that an optimum strength will be obtained at a level of 6.8 percent of aromatic chlorine compounds. Furthermore, extrapolation of the data beyond the measured 10 percent upper limit employed in this experiment predicted that the strength would fall off to a value equalling the strength of the bars containing no additive at a value of 13.8 percent of aromatic chlorine compounds. Furthermore, continuedextrapolation revealed that a 16 percent addition of aromatic chlorine compounds would yield strengths which were safe for grinding wheel operation.

3 From the foregoing tests it can be seen that the wheels were prepared in such a way that the aromatic compound effectively replaced the air that constituted some of the voids. Although the density of the test bars 7 increased, it was determined that the wheel either had better cutting characteristics or a longer life.

Grinding wheel performanceis normally determined by two criteria. The first criterion involves the ratio of metal removed to wear of the wheel on a volumetric basis. Thus, the foregoing ratio will be low where the volume of metal removed is high, but the volume of the lene is much preferred since it does not have an irritating odor and otherwise performs satisfactorily in achieving the novel results of the present invention. It has been further determined that the other two compounds specified hereinabove (decachlorobiphenyl and hexachlorobenzene) are also quite satisfactory in grinding performance, but these two compounds tend to release a very irritating odorduring the grinding operation and therefore it is somewhat difficult to work with these compounds. For this reason only, octachloronaphthalene is the preferred aromatic chlorine compound that is usable in the invention. However, it should be kept in mind that the preferable range of l to 16 percent by weight applies to all three of the aromatic chlorine compounds that are usable in the invention.

In order to demonstrate the improved and unique grinding performance of the present invention, the following formulation, by weight, was prepared:

Abrasive No. l 84.68%

1/3 No. 14 mesh fused A1 Abrasive 1/3 No. 16 mesh fused A1 0 Abrasive l/3 No. 20 mesh fused A1 0 Abrasive Powdered Bond No. l 13.46%

62.92% powdered phenolic resin (two-step hexamethylene tetramine catalyzed resin). 25.78% Cryolite (Na AlF 11.30% Calcined Lime (absorbs water of condensation; is needed when per cent of air is less than l8% by volume) Furfurall.26%- -(Furfuraldehyde) Carbosota-0.59%--(Crude neutral fraction of coal tar) To this above formulation, which totals 100 percent by weight, was added 2.16% weight of octachloronaphthalene. The formulation was pressed to a density of 2.575 gms/cc to produce a type 1 straight wheel having a 6 inch diameter by 1 inch thickness, with a /8 inch arbor hole. This formulation, thus pressed to the above density, contained a total of 21% voids, of which 18% was air and 3% was octachloronaphthalene.

The foregoing wheel was compared with a somewhat similar formulation as follows:

No. l Abrasive mix: 87.61%

11%PTwdered Bond 2: 10.8 3%- anthracene 4 89% Powdered phenolic. resin (as above); 1 1% Cryolite Furfural: 1.11%

Carbosota: 0.45%

The foregoing wheel was pressed to a density of 2.48 gms/cc with the same dimensions as the previous wheel. This formulation, thus pressed to this density, contained 22% voids, all of which was air.

It was noted that the wheel containing the aromatic chlorine compound not only was harder and therefore had a longer life, but its metal removal rate actually increased over the foregoing formulation without the aromatic chlorine compound.

A precise comparison of wheel performance is set forth below:

Volume" Metal G-Ratio Wheel Removal G-Ratio* (cu. in. of Type of Wear Rate lbs.- of metal metal/ Wheel (lbs/hr.) (lbs/hr.) per lb. wheel cu. in. Convenof wheel) tional 1.47 7.86 5.35 1.68 Wheel with 1.20 8.32 6.91 2.26 Aromatic Chlorine Compound *The ratio of metal removed to wheel Wear on a gravimetric basis.

"The ratio of metal removed to wheel wear on a volumetric basis.

It can be seen from the foregoing table that the metal removal rate was improved by 6 percent using the pres ent invention while at the same time there was a 34 percent improvement in G-ratio.

Hereinafter, octachloronaphthalene will be referred to as O.C.N..

Another standard formulation and aromatic chlorine compound formulation are compared below, wherein henuantitissars b.v.wi ht;.-

Abrasive Grain No. 2-86.48%

50% No. 16 mesh fused A1 0 50% No. 20 mesh fused A1 0 serni friable) Powdered Bond Blend No. 1- 13.46%

Furfural 1.26%

Carbosota 0.59%

The foregoing mix was pressed into three type 6 cup wheels having a diameter of 6 inches, a thickness of 2 /4inches with a threaded steel bushing having a inch diameter and l 1 threads per inch. The wheel was pressed to a density of 2.575 gms/cc and contained a total of 21% voids, of which 18% was air and 3% was O.C.N.

The foregoing formulation was compared with a stan- Metal G-Ratio Wheel Removal G-Ratio cu. in. Type of Wear Rate (lbs. of metal of metal Wheel lbs/hr lbs/hr per lb. wheel) per cu. in.

wheel Conven- 2.56 14.92 5.83 1.82 tional Wheel With 1.55 15.30 9.87 3.24 Aromatic Chlorine Compound It can be seen from the foregoing table that the metal removal rate was improved by 2.5% using the present invention while at the same time there was a 78% improvement in G-ratio.

it is to be noted that the wheel containing the arcmatic chlorine compound has less voids than the conventional wheel. It was therefore harder and had a longer life than the conventional wheel, but its removal rate was actually higher than that of the conventional wheel.

It is also to be noted that the foregoing wheels as well as all other wheels and test bars set forth in connection with this disclosure are simply formulated according to known practices by combining the various components in a standard mixing action. Thereafter, the mix is pressed to a desired density and is then cured at elevated temperature for a given time. Normally, the socalled green wheels are placed in the oven at room temperature and the temperature is then gradually raised for 16 hours until a maximum of 350 F. is achieved. The cure then continues for 24 hours at 350 F. The cured wheels are then allowed to cool.

Yet another test was made wherein a wheel, including an aromatic chlorine compound, was tested in comparison with a so-called standard wheel. The wheel made in accordance with the present invention had the llgwin ,in rssiisn bxweieht;

Abrasive Grain No. 3 83.42%

1/3 No. 16 mesh fused A1 Abrasive 1/3 No. 20 mesh fused A1 0 Abrasive l/3 No. 24 mesh fused A1 0 Abrasive Powdered Bond No. l 14.58% (same as previous No. 1 bond) Furfural 1.36%

Carbosota 0.64%

To the above, which totals 100%, was added 2.34% of O.C.N. The foregoing mix was pressed to a density of 2.715 gms/cc to produce wheels having a 6 inches diameter by l/2 inch thickness with a /8 inch arbor hole, type No. l, fiberglass reinforced wheel. This wheel, thus pressed, consisted of 15.38% voids, of which 12% was air and 3.38% was O.C.N.

The standard wheel corresponding to the above formulation had the following ingredients:

Abrasive Grain No. 3 83.41%

Powdered Bond 14.03%

71% Powdered Phenolic Resin 29% Cryolite Liquid Phenolic Resin (Wetting Agent) 2.10%

Neutral Oil 0.46%

The foregoing standard wheel was pressed to a density otifigifislcc, and possessed l 8 7e voids, all air.

In tests (average of two wheels) it was determined that the standard wheel had a rate of metal removal (lbs/hr) of 6.51 whereas the wheel containing the aromatic chlorinated compound had a rate of metal removal of 6.99. At the same time, both the standard wheel and the wheel including the aromatic chlorinated compound had a wear rate in lbs/hr of 1.12. Thus, whereas the standard wheel had a higher porosity, nevertheless, it still had a lower cutting rate as compared with the grinding wheel including the aromatic chlorine compound. Hence, a wheel incorporating the aromatic chlorine compound had a superior rate of metal removal while it had the same rate of wear as the standard wheel.

Further tests have been run utilizing decachlorobiphenyl and hexachlorobenzene. However, as previously indicated, these two compounds give off a very irritating odor, and thus are not as desirable as octachloronaphthalene, although it is to be emphasized that all three compounds, when incorporated in grinding wheel formulations within the ranges specified in this invention, give rise to superior results. These superior results are either in the formof an improved cutting action or longer life or both.-

The octachloronaphthalene usable in the present invention is a hard resinous solid with a melting point of about 185 C. and has a chlorine content of about This compound has extremely low volatility and is stable at temperatures up to its melting point.

Without further elaboration, theforegoing will so fully illustrate our invention, that others may, be applying current or future knowledge, readily adapt the same for use under various conditions of service.

What is claimed as the invention is:

1. An organic bonded abrasive product having a unique void replacement completely chlorinated hydrocarbon filler material, said product including abrasive material and an organic binder compatible with said filler material and abrasive material, the improvement comprising adding to said abrasive material and binder an effective amount of octachloronaphthalene, present in a proportion by weight of 1 to 16 per cent of total abrasive material and binder.

2. An organic bonded abrasive product having a unique void replacement completely chlorinated hydrocarbon filler material, saidproduct including abrasive material and an organic binder compatible with said filler material and abrasive material, the improvement comprising adding to said abrasive material and binder prior to curing an effective amount of octachloronaphthalene, said octachloronaphthalene, abrasive material and organic binder are mixed together, pressed to size and then cured, said octachloronaphthalene being present in a proportion'of about 6 to 8 per cent by weight. 

2. An organic bonded abrasive product having a unique void replacement completely chlorinated hydrocarbon filler material, said product including abrasive material and an organic binder compatible with said filler material and abrasive material, the improvement comprising adding to said abrasive material and binder prior to curing an effective amount of octachloronaphtHalene, said octachloronaphthalene, abrasive material and organic binder are mixed together, pressed to size and then cured, said octachloronaphthalene being present in a proportion of about 6 to 8 per cent by weight. 